Composition study of a mortar appropriate for masonry cavities and joints

It is well known that unreinforced masonry behaves as a quasi-brittle material when subjected to seismic loading. The construction in unreinforced masonry is usually not allowed in regions with moderate to high seismic hazard. The alternative to unreinforced masonry and even to reinforced concrete and steel construction is reinforced masonry, which appears to perform adequately under seismic loading. This work deals with the challenging issue of contributing to the definition of a fast and simples construction system using reinforced masonry, by replacing the grout by a general purpose bed mortar, capable of being used also to fill vertical cells with vertical reinforcement. The major difficulty is to find a mortar that is also suitable to fill vertical hollow cells of concrete units. This work presents preliminary results from the study of different mortars, corresponding to different compositions, in order to find appropriate workability and sufficient fluidity. The analysis is based on a comparative study including the characterization of the fresh mortar properties, such as workability, and the hardened properties, such as modulus of elasticity, flexural strength and compressive strength. The assessment of the mortar adequacy to fill the hollow cells is also analyzed by the execution of masonry prisms, followed by a qualitative analysis of the fill.